feat(core): Implement RFC-6570 URI template matching and expansion utils (#502)

[kpavlov]

Implements RFC-6570 URI Templates (UriTemplate, UriTemplateMatcher, UriTemplateParser) in kotlin-sdk-core with full Level 1–4 expansion and regex-based reverse matching.

• Expansion — all 8 operators ({var}, {+var}, {#var}, {.var}, {/var}, {;var}, {?var}, {&var}), prefix modifiers ({var:3}), and explode modifiers ({var*}) for string, list, and associative-array values.
• Matching — UriTemplate.match(uri) extracts all variables from every expression (including multi-variable {?x,y}) and returns a specificity score (literal character count) for disambiguating overlapping templates.
• Performance — template parsed eagerly on construction; compiled Regex cached lazily via matcher() (only when matching is needed); pre-allocated OpInfo singletons for all 8 operators; literal-only templates skip variable extraction entirely.

Motivation and Context

Prerequisite for #502, see resource-templates

How Has This Been Tested?

Implemented unit tests for conformance with all expansion levels and path operators.

Breaking Changes

No

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update

Checklist

• I have read the MCP Documentation
• My code follows the repository's style guidelines
• New and existing tests pass locally
• I have added appropriate error handling
• I have added or updated documentation as needed

Additional context

[codecov-commenter]

Codecov Report

❌ Patch coverage is 90.21277% with 23 lines in your changes missing coverage. Please review.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...textprotocol/kotlin/sdk/utils/UriTemplateParser.kt	87.00%	0 Missing and 13 partials ⚠️
...extprotocol/kotlin/sdk/utils/UriTemplateMatcher.kt	80.95%	0 Missing and 8 partials ⚠️
...delcontextprotocol/kotlin/sdk/utils/UriTemplate.kt	97.84%	0 Missing and 2 partials ⚠️

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